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Thread: Rh side carb leaking mistery Bmw r100s

  1. #1

    Rh side carb leaking mistery Bmw r100s

    Hello to all , i hope everyone is doing well .
    I need your help again ..
    Before 1.5 months i rebuild the carbs i purchased from motobins guskets o rings jets floats and valve floats.. the problem i have is that the rh side is leaking fuel from the overflow tube... i adjust the fload height many many times i canít remember how many times i drop the bowl and adjust the fload level...when i pressing the float with my hand petrol is stoping float is moving frealy i polish the valve seat as well.. i am desperat
    I start thinking thAt the floAt valve that I purchased has a problem or is multifunctional .
    Anyone has any experience with motobins items ?
    Is there anything else that i can do?

  2. #2
    Liaison 20774's Avatar
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    Bummer...you would think that new parts fixes the problems. I wonder if there's a problem with the float...maybe it sinks? You can drop the floats into a container of gasoline. A good float will sit in the gas with about 1/3 above the level of the fuel. If it rides lower than that, the float is bad.
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  3. #3
    I learn with japan carbs keihin mikuni etc this is my first time working on bing.. as en example on keihin leaking from overflow tubes changing the float valves will solve the problem....i am a little dissapointed to be honest :-)..

    the floats are brand new as well

  4. #4
    Liaison 20774's Avatar
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    Hopefully others will have ideas as well. You might want to follow this thread of another member having overflow issues with a Bing carb:

    https://forums.bmwmoa.org/showthread...Overflow-R75-5
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  5. #5
    Gerard jagarra's Avatar
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    It has to be either the float either dragging on the side of the bowl, a punctured float or another thought, can you check how far the float falls when the bowl is empty, could it be that it is binding as the bowl fills because the needle is moved out of position?
    1994 R1100RS-(5/93)-,1974 R90/6 built 9/73,--1964 Triumph T100--1986 Honda XL600R

  6. #6
    Another thread you may want to follow.

    It may just be familiarity tunes the mental antennae to problems... I've only ridden bikes with bings... but seems I've heard plenty an anecdote
    about leakage being in the nature of bings. In my own case, I've had them leak for a spell, maybe some days on end, and then stop it entirely. No adjustment or remedy performed.
    The situation just disappeared.

    From that thread...

    I once sent a fairly intemperate letter to Bing on this very topic (yes it was that long ago in the time before emails). They replied "We do not make petcocks, we make carburettors. When you leave your bike, turn the petcocks off."

    Never had a problem since, although quite why the Germans cannot design a needle and seat that works as well as the Japanese manufacturers is somewhat beyond me.
    These bikes have character aplenty, some of it less than welcome

    It has to be either the float either dragging on the side of the bowl....
    This I can confirm on my '83 R65. Must be a very close tolerance between float and bowl. I've had this happen twice when refitting the bowls. I may even have caused it ham handedly while reassembly. VERY gently tweaked the float into line and fixed the problem. I only deduced it because I'd exhausted all other possibilities and then tweaked/bent the float more perfectly centered on a hunch. Stopped leaking immediately.

  7. #7
    Your problem sounds similar to the one I batteled with my R90/6. Both float bowls would almost empty at night after I shut off the fuel. Rebuilt the carbs, same problem. Reading through Snowbums site bmwmotorcycletech.info/carbuetors-that-piss.htm Ended up needing to reseat the overflow tubes in each float bowl. Leaking happens between outer diameter of the overflow tube where it passes through the float bowl. As snowbum suggests place float bowl upside down on solid surface , bottom of bowl facing upwards. Used a small tapered pick or awl and placed end of pick into bottom end of tube. Then carefully hit handle of pick four or five times with a small hammer mine is 4 oz. First attempt improved but did not stop the leaking. Determined my cheap pick may not be precision made and just hammering down on it my not have sealed the tube 360 degrees to inside of bottom carb inner surface. On second attempt I inserted pick, hammered downward 4 or 5 times, rotated pick about 45 degrees , hammered downward 4 or 5 times again. Repeated rotating pick 45 degrees till I went through whole 360 degrees. Did this with each float bowl and so far the leak has stopped 100 percent. Don't know if your float bowls are the same but thought it may be worth mentioning to you.

  8. #8
    Day Dreaming ... happy wanderer's Avatar
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    Another often overlooked possibility is that the floats and new needles are fine but the needle _seat_ is worn. Assuming you've made sure there is no debris in the seat and sounds like you have this might be the problem.

    Check for overflow tube leaks as per the previous post. Easy to do; just fill the bowl with gas on the workbench in a container and see if any seeps out the bottom. Tube not seated properly if it does. See Snowbum's page as recommended.

    If not, what some do and this is a delicate operation but remove the carb so you can work on it upside down. Remove the float and needle. Get a standard pencil with a new pink eraser on the top. Cut out some super fine (800 grit) sandpaper and glue it to the top of the eraser. Once the glue is set, trim the paper to be round on top following the eraser circumference as best you can.

    Gently. GENTLY insert the eraser down into the needle seat and slowly turn it round and round with gentle pressure. Kind of like delicate valve seat lapping... One guy wrote about doing this with toothpaste in the field and it worked! Take a good look in there with a flashlight before and as you do this to monitor your progress. With really good eyes or a magnifier you may be able to see the wear on the seat. Once it is nice and shiny and you have removed just the tiniest amount of brass (visible on the paper) try again.

    These seats wear out and replacing them is a bugger so many have done this to get rid of the slight wear on the seat that causes minor leaks even with a new needle.
    MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
    '81 R80G/S, '82 R100RS, '00 R1100RT

  9. #9
    Hello to all thank you for your replies... i have done the pencil method and grind some of the seat ... i also check the bowl on the workbench if its leakes... and ofcourse is not leaking..

    i will try the method to seat the overflow tube is the only thing that i didn't do

    ι note that if i adjust the tongue of the floats to open the float valve is not allowing fuel to run to the float bowl... so i assume that float valve is working properly????. if i adjust as per manual i have a leak when bike is park on center stand... if the bike is running i don't have the leak....

    most probably my fuel seat is worn ...

  10. #10
    update on the thread... i order 2 seats from bing usa... as soon as i receive them i will post the result..

  11. #11
    Airhead or Nothing
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    I did the seats on my RS carbs about two months ago, when you follow the instructions from Bing, the job is very straight forward, and not difficult
    "Punk rocks what its all about" J. Strummer

  12. #12
    Hello to all i will like to update my thread. i receive the seats for Bing last week install them took me around 10 minutes .... and now the bike is free of leaking gas out the overflow tube. and of course a happy airhead owner.....42678876_615755105493518_15286054894436352_n.jpg42714073_250734352300382_530643140701323264_n.jpg

  13. #13
    Liaison 20774's Avatar
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    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  14. #14
    Day Dreaming ... happy wanderer's Avatar
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    Hey! Winner winner chicken dinner!
    Good to hear you found and fixed the issue. Surprised that grinding them flat again did not work but maybe just too worn to get a good seal.

    I've never had to replace the seats yet but it sounds like it was not too difficult. Just wondering if you could actually see the wear on the seat from the needle or maybe they get destroyed when you remove them? I'm a curious fellow.
    MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
    '81 R80G/S, '82 R100RS, '00 R1100RT

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